Corethrella (Corethrella) quadrivittata Shannon and Del Ponte, 1928

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 155-159

Corethrella (Corethrella) quadrivittata Shannon and Del Ponte

Corethrella quadrivittata Shannon and Del Ponte 1928:101 . Type locality: Tres Pozos, near Embarcación, Salta, Argentina. Lectotype ♂ designated by Casal in Belkin et al. 1968:16 (INMA). Lane 1942:122, 1953:90. Lane and Cerqueira 1958:561. Balseiro and Spinelli 1984:193.

Corethrella kummi Lane 1942:121 . Type locality: vicinity of Salvador (restricted by Belkin et al. 1971: 28), Baia [=Bahia], Brazil. Holotype ♀ (BMNH). Lane 1953: 90. New synonym.

Corethrella dyari Lane 1942:125 . Type-locality: Darien, Canal Zone, Panama. Holotype ♀ (USNM). Lane 1953: 91. New synonym.

Corethrella izquierdoi Vargas 1952: 59 . Type locality: Tenosique , Tabasco, Mexico. Holotype ♂ (IDRE). New synonym.

DIAGNOSIS: Male and female adults: only extant species of Corethrella in the New World with the wing with four transverse bands: basal, subbasal, midlength and subapical band (the latter with no dark scales on these veins extending to the apex of the wing) (Figs. 64I, 71A), with the halter dark brown (equal to that of the scutellum) and with the hind tibia with both basal and apical darker pigmentation ( Fig. 54C).

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view laterally elongate (as in Fig. 12H). Four large setae on frons between ventromedial area of ommatida (as in Fig. 16G). Antenna light brown; pedicel with at least one distinctive, more elongate, stout, dorsal or dorsolateral seta; flagellomeres as in Fig. 23I, sensilla coeloconica (as in Fig. 15G) distributed as in Table 1; flagellomere 13 with well-developed apical bifurcation. Palpus pale to light brown, in some with apical portion of segment 5 more darkly pigmented; segment 3 of nearly constant width. Thorax (as in Fig. 54C): Dark brown. Posterior portion of dorsocentral row with group of about 4 elongate setae. Prescutal suture short, not extending more than half way to dorsocentral row of setae. Anterior anepisternum divided diagonally by sinuous suture, dorsal portion about equal to ventral portion. Ventral portion of posterior anepisternum triangular, uniformly brown, with anterodorsal margin thick. Wing (Fig. 64I): Apex of R 2 equal to apex of M 1. Anterior margin with differently, discretely pigmented scales (indicating anterior margins of transverse bands), with four bands of dark scales: basal, subbasal, midlength and subapical, with latter not extending to apex of wing; veins (other than costa and wing margin) with well-developed scales. Halter as dark as scutellum. Legs (as in Fig. 54C): Dark brown, with apical 1/5 of hind femur more lightly pigmented, hind tibia with basal, apical darker, non-discrete pigmentation, at least mid-, hind leg tarsomeres 2–4 with banding. Mid-, hind femora with slen- der scales (also some in patch of whip-like setae on posterior portion of hind tibia). Midleg with thick, subapical setae on each of at least tarsomeres 1–3. Apices of fore-, midleg fifth tarsomeres undivided, with claws slightly subapical to apical (as in Fig. 75F). Claw of foreleg longer than those of mid-, hind leg. Each claw without inner tooth. Anterior claws of each leg without a basal prong. Foreleg claws unequal. Midleg claws equal. Foreleg third tarsomere shorter than fourth tarsomere. Empodia slender. Abdomen (Fig. 80B): Dark brown. Genitalia (Fig. 95B): Gonocoxite dark brown basally, with apical 1/4–1/2 more lightly pigmented, gently tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with welldefined dorsal row of setae, with setae 1–3 thicker than others, with row restricted to dorsal portion of gonocoxite. With one dorsomedial stout seta, somewhat tapering from base. Gonostylus (partially extended) basal 4/5 straight, apical 1/5 evenly curved, basal half thicker, apical half slender, tapered apically; one elongate, slender subbasal seta, situated anteriorly or anteroventrally; apical seta slender, elongate, bifurcating (possibly simple in some). Aedeagus slender, elongate, tapering gradually to apex, pointed apically, with lateral margins fused at apex.

Female adult. Descriptive statistics: see Tables 6–11. As for male, with following differences. Head: Coronal suture elongate, extending ventrally past ommatida (as in Fig. 16G). Antennal flagellomeres 1–5 each with apex darker brown, flagellomeres 6–13 medium brown; with flagellomeres as in Fig. 30L, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 18X) squarish. Mandible with small, pointed teeth. Palpus as in Fig. 35D. Wing (Fig. 71A). Legs ( Fig. 54C): As for male but apical 1/3 of hind femur more lightly pigmented. Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Dark brown with, in some, segments 8, 9 slightly darker. Cercus dark brown.

Pupa. Described by Lane and Cerqueira (1958), Balseiro and Spinelli (1984). Thorax: Scutum, metathorax without spherical sensory pits (metathorax with blunt knob which may be homologous). Respiratory organ (Fig. 103B): Tubular, with apical portion flattened. Abdomen (Fig. 109C): Segments 3–7 not expanded laterally. Paddle long, slender; apicodorsal thick spine articulating; apicoventral seta longer than thick spine.

Larva. Described by Lane and Cerqueira (1958), Balseiro and Spinelli (1984).

Egg. With peripheral floats; laid individually.

DISTRIBUTION AND BIONOMICS: Corethrella quadrivittata has a broad distribution in the New World and is known from Mexico, Costa Rica to Suriname, south to Argentina and Brazil (Fig. 135). The Mexican record is based on a single poor specimen (type of C. izquierdoi ) and otherwise the species is only known from Costa Rica to Suriname south. The Mexican record needs confirmation through additional collecting. Adults have been collected at altitudes ranging from 0–1400 m (possibly as high as 1500 m). However, only one male and one female came from the highest elevation (in Costa Rica); otherwise most specimens were collected below 108 m, with specimens from Maracay, Venezuela collected at 547 m. Most adult specimens were collected using light and Malaise traps, with a few present in samples from frog-call traps in Costa Rica (using Hyla gratiosa ), Panama (using Physalaemus pustulosus - by X. Bernal) and Guyana (using Scinax ruber - by G. Bourne). Generally, adult C. quadrivittata were uncommon in the frog-call traps run in Costa Rica. For example, of at least 1500 Corethrella collected at La Selva Biological Station in Costa Rica, March 1–2, 2004, only two female adult C. quadrivittata were present.

The serrate mandibles of the female adults and their attraction to frog calls suggest that they feed on frog blood in nature. Larvae and pupae have been collected from lagoons in Costa Rica and Balseiro and Spinelli (1984) found them associated with aquatic plants of Azolla filiculoides and Salvinia sp. One specimen from Panama was reared from a pond. Shannon and Del Ponte (1928) recorded C. quadrivittata larvae from a lagoon with aquatic plants, ( Pistia and others), but it is uncertain whether these larvae were actually reared to adults. I have not examined any of these latter specimens to confirm their identity. The specimens from the Belkin “Mosquitoes of Middle America” project are identified in Table 12.

Guanacaste Province in Costa Rica experiences a pronounced dry season from about November to the beginning of May. During this dry period some flood plains near Bagaces are reduced to isolated lagoons and C. quadrivittata adults were consistently present in the Malaise traps placed near these lagoons during that time. Otherwise, there were a few specimens collected during the wet season, when large areas are flooded, in July–September. This suggests that its life cycle is coordinated with the seasons at least in that area. Alternately, it may be that the flooded habitat during the wet season disperses the population of C. quadrivittata , so that they are not very common in Malaise trap samples.

Adults were reared from eggs laid by a female collected with a frog-call trap at 5 km NE Tárcoles, Costa Rica (Carara National Park). Eggs floated individually at the surface and all hatched in five days. Hatching larvae escaped the egg shell through one end which was partially detached. Three first instars were placed in a thin film of water in a petri dish to determine if they used their prolegs to transport themselves but they merely lashed about in typical culicid fashion. All larvae of each instar anchored themselves with both pairs of strong setae at the apex of the siphon and were often in the meniscus of the petri dish. Compared to the larvae of C. ranapungens and C. puella , they were more active, relocating themselves regularly and spending more time at the surface. They fed in the typical manner described in the generic synopsis. Larvae could extend their body lengths to capture prey by 74–81% (n = 5). A moribund fourth instar was placed near a healthy larva which promptly captured and ingested most of it in 10 minutes, and then snipped the remaining head capsule off with its mandibles. Generally prey items are ingested much more quickly—a nearly equally sized mosquito larvae was ingested in four minutes.

The pupae of C. quadrivittata hung straight down and the elongate apices of their two respiratory organs abutted on the water surface, forming a single emergent area. Pupae were lethargic and non-mobile for most of their development but were capable of rapid dorsoventral movement of the abdomen shortly before emergence as an adult.

TAXONOMIC DISCUSSION: Males and females were associated through the shared presence of a common pigmentation pattern and were collected together at a few places in Costa Rica and one in each of Colombia and Argentina. In addition, males and females have been reared from similar larvae and pupae in Costa Rica, Panama, and Argentina.

Examination of the lectotype of C. quadrivittata and holotypes of C. kummi , C. dyari and C. izquierdoi indicate that these are presently indistinguishable and I therefore consider the latter three names to be synonyms of C. quadrivittata . Lane (1953) gave the most recent key to Neotropical Corethrella and he recognized each of C. quadrivittata , C. kummi , and C. dyari as valid species. Corethrella izquierdoi was not included as it was likely published too late for inclusion). He distinguished C. kummi on the basis of there being only three wing bands present. As discussed below, this interpretation was based on a misassociated wing. The present female holotype had one attached wing which clearly shows four wing bands, typical of C. quadrivittata . Lane distinguished C. dyari and C. quadrivittata on the degree to which the tarsi were banded but I cannot see any differences in the types (or with other C. quadrivittata ). The holotype of Corethrella izquierdoi , the only specimen of C. quadrivittata north of Costa Rica, is in very poor condition (see below) and further fresh material may result in this name being resurrected, but for the present it is indistinguishable from other material of C. quadrivittata .

Shannon and Del Ponte (1928) described C. quadrivittata on the basis of five males, 15 females and some larvae (number unknown). Casal (in Belkin et al. 1968) designated a male lectotype which has been placed on a microscope slide for this study. Two females (now on slides; INMA, USNM), 1 male (pinned; INMA) and one specimen with only a damaged thorax and one wing (pinned; INMA) were labeled from Embarcacion, 3- V-1926. This locality and date are given by Shannon and Del Ponte (1928) in their list of specimens and are here considered paralectotypes (and have been labeled as such). A bare pin with this locality and date was in the INMA and likely represents a missing paralectotype. It is unknown where the remaining paralectotypes are.

The holotypes of C. kummi and C. dyari were originally on pins but were placed on microscope slides for this study. Corethrella dyari was described on the basis of the holotype female and four female paratypes but I have been unable to locate the paratypes. Vargas (1952) mentions a single male holotype in his description of C. izquierdoi (specifically recording only one male in the abstract). A male pinned specimen in IDRE is identified as C. izquierdoi and collecting information is that reported by Vargas (1952) for this species. I consider this to be the holotype and have added a label to identify it as such. It is missing its flagellomeres, wings, right midleg tibia and tarsomeres, left midleg and both hind legs, and most of the abdomen (some of these likely on the accompanying slide). A separate slide labeled as holotype and providing matching locality and date includes four wings, one hind leg and crushed parts of the genitalia of three males (the apices of 5 gonostyli are present). I have arbitrarily chosen two wings as those of the holotype and indicated this on the slide with black ink on the coverslip with an “H” and two lines to the two wings. I have circled the genitalic parts of what I consider to be the holotype. Further to this, the genitalia are stained red and the pigmentation of the gonocoxites is therefore uncertain.

The female holotype of C. kummi was originally pinned, with a wing in a glycerine vial below. This wing is clearly that of a male and must have come from another, unknown, specimen. This misassociated wing does indeed have only three wing bands as recorded by Lane (1942, 1953) and belongs to an unknown species. I have indicated this on the coverslip with a “?” and a line going to that wing.

The relative length of the female first flagellomere is variable in this species but I could not see any pattern allowing the separation of two forms.

The one specimen from Guyana is in the possession of G. Bourne (University of Missouri-St. Louis) .

MATERIAL EXAMINED: Lectotype, adult male on microscope slide, labeled “ Corethrella quadrivittata Shannon & Del Ponte ”, “ Lectotypus ”, “Tres Pozos, Salta, 20.4.27", “Shannon & Shannon” ( INMA); paralectotypes: 1 ♂, pinned ( INMA) , 2 ♀ on slides ( INMA, USNM) , 1 unknown sex, pinned ( INMA), all from Embarcación, Salta, Argentina, 3-V-1926. Holotype, female adult on microscope slide, labeled “ Corethrella kummi Lane, 1941 ", “holotipo”, “ Holotype ”, “ Brazil: Bahia. 1931. H.W. Kumm B.M. 1933-503” ( BMNH) . Holotype, female adult on microscope slide, labeled “ Corethrella dyari J. Lane det 41", “P32-a”, “Darien, C.Z., Pan. VIII.2.1923”, “Dyar & Shannon” ( USNM) . Holotype, male adult on pin and microscope slide, pinned portion labeled “ Holotype Corethrella izquierdoi Vargas, identified by A. Borkent, remaining parts on slide”, “ Corethrella (C) izquierdoi ”, “Tenosique, Tab. Col. Dr. L. Vargas, IV-1941 ”; slide labeled “ Corethrella izquierdoi , #6251, Tenosique, Tab. Col. Dr. L. Vargas, IV-1941, Lampara Trampa”, “Holoaedotipo ♂ ”, “ Holotype Corethrella izquierdoi Vargas, remaining parts on pin” ( IDRE) . Other material: 6 ♂, 5 ♀, Bagaces , Palo Verde National Park, Guanacaste, Costa Rica, 10-50 m, 5-I–7-II-2000 (4 ♂, 2 ♀, INBC; 2 ♂, 3 ♀, CNCI) ; 4 ♂, 2 ♀, as for previous locality but 10-IX–12-X-1999 ( INBC) ; 2 ♂, 3 ♀, as for previous locality but 6-X–8- XI-1999 ( INBC) ; 1 ♂, 3 ♀, as for previous locality but 2-XI–11-XII-1999 ( INBC) ; 4 ♂, 5 ♀, as for previous locality but 8-XI–5-XII-1999 ( INBC) ; 2 ♂, 6 ♀, as for previous locality but 9-XII–1999 - 5-I-2000 ( INBC) ; 5 ♂, 5 ♀, as for previous locality but 5-XII-1999 – 5-I-2000 ( INBC) ; 4 ♂, 5 ♀, as for previous locality but 6-I–18- II-2000 ( INBC) ; 4 ♂, 5 ♀, as for previous locality but 8–19-II-2000 ( INBC) ; 3 ♂, as for previous locality but 7- II–6-III-2000 ( INBC) ; 3 ♀, as for previous locality but 17-VIII–13-IX-1999 ( INBC) ; 7 ♂, 1 ♀, as for previous locality but 6-VII–17-VIII-1999 ( INBC) ; 3 ♂, as for previous locality but 16-VII–17-VIII-1999 ( INBC) ; 1 ♂, 2 ♀, as for previous locality but Estr. E. campo Aterrizaje, 5-I–7-II-2000 ( INBC) ; 3 ♂, as for previous locality but Est. Palo Verde , 10–50 m, 14–20-XI-2004 ( INBC) ; 1 ♀ with larval and pupal exuviae, as for previous locality but Laguna Varillales , 10 m, 27-XI-2002 ( CNCI) ; 1 ♂, Laguna in front of station, Palo Verde National Park, Bagaces, Guanacaste, Costa Rica, 10 m, 27-XI-2002 ( INBC) ; 1 ♀, Isla Saino , Nicoya P.N. Palo Verde, Guanacaste, Costa Rica, 0–10 m, 16–20-XI-2004 ( INBC) ; 4 ♂ each with larval and pupal exuviae, 3 ♀ each with larval and pupal exuivae, 1 ♀ with pupal exuviae, Laguna Palmar , 2.5 km NE Pitahaya, Pitahaya, Puntarenas, Costa Rica, 25 m, 28-XI-2002 (2 ♂, 2 ♀, INBC; 2 ♂, 2 ♀, CNCI) ; 1 ♂, 1 ♀, Fronteen con Panama, Mellizas Sabalito, Coto Brus, Puntarenas, Costa Rica, 1400–1500 m, 28-XII-1995 ( CNCI) ; 5 ♂, 2 ♀, 5 km NE Tárcoles , Costa Rica, 20 m, 17-VIII-1993 ( CNCI) ; 2 ♂, 5 ♀, as for previous locality, 2-IX-1993 ( CNCI) ; 1 ♀, Tárcoles , Costa Rica, 10 m, 11-XI-1993 ( CNCI) ; 1 ♀, La Selva Biological Station , Puerto Viejo de la Sarapiqui, Heredia, Costa Rica, 40 m, 2-III-2004 ( CNCI) ; 1 ♂, 3 km S. Tocumen Airport , Tocumen, Panama, 10 m, 27-VII-1972 ( USNM) ; 4 ♀, Tocumen , Panama, 15 m, 2-IX-1952 ( USNM) ; 1 ♀, as for previous locality but 17-XII-1952 ( USNM) ; 1 ♀, as for previous locality but I-1953 ( USNM) ; 1 ♀, from 9°07.0'N, 79°41.9'W, Gamboa , Panama, 27 m, 12-VII-2003 ( CNCI) ; 1 ♀, Pacora , Panama, Panama, 20 m, 5-I-1953 ( USNM) ; 1 ♂, 4 ♀, 13 km NE Monteria , Cordoba, Colombia, 10 m, 5–6-X-1969 ( USNM) ; 1 ♀, Finca La Corocora , Villavicencio, Meta, Colombia, 450 m, 15-VII-1971 ( USNM) ; 1 ♀, as for previous locality but 17-VII-1971 ( USNM) ; 2 ♂, 7 ♀, Sector Mata-Mata , PNN Amacayacu, Amazonas, Colombia, 150 m, 11–24-IV-2000 ( CNCI) ; 1 ♀, Quisto Cocha , Iquitos, Loreto, Peru, 108 m, 8–10-II-1984 ( CNCI) ; 2 ♀, Maracay , Venezuela, 24-V-1927 ( USNM) ; 1 ♀, as for previous locality but 1-VI-1027 ( USNM) ; 1 ♀, CEIBA Biological Center , 06°29 N, 58° 13 W, Guyana, 20-III-2006 ; 1 ♀, Ma Retraite , Paramaribo, Suriname, 5 m, 22–27-VIII-1963 ( USNM) ; 1 ♀, 5 km N Republiek, Zanderij , Para, Suriname, 20 m, 29-IX–3-X-1963 ( USNM) ; 1 ♀, as for previous locality but 13–19-X-1963 ( USNM) ; 2 ♀, Nariva , “Bush Bush Forest “, Trinidad and Tobago, 1 m, 16-I-1964 ( USNM) ; 2 ♀, Salobra , Mato Grosso, Brazil, 1939 ( USNM) ; 1 ♂, 1 ♀, Los Talas , Berisso, Buenos Aires, Argentina, 6 m, 26-II-1982 ( MLPA) .

DERIVATION OF SPECIFIC EPITHET: The name quadrivittata (four bands) almost certainly refers to the four wing bands noted by Shannon and Del Ponte (1928).